title: Structure and VP16 binding of the Mediator Med25 activator interaction domain.
abstract: Eukaryotic transcription is regulated by interactions between gene-specific activators and the coactivator complex Mediator. Here we report the NMR structure of the Mediator subunit Med25 (also called Arc92) activator interaction domain (ACID) and analyze the structural and functional interaction of ACID with the archetypical acidic transcription activator VP16. Unlike other known activator targets, ACID forms a seven-stranded β-barrel framed by three helices. The VP16 subdomains H1 and H2 bind to opposite faces of ACID and cooperate during promoter-dependent activated transcription in a in vitro system. The activator-binding ACID faces are functionally required and conserved among higher eukaryotes. Comparison with published activator structures reveals that the VP16 activation domain uses distinct interaction modes to adapt to unrelated target surfaces and folds that evolved for activator binding.
authors.affiliation: Gene Center and Department of Biochemistry, Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-Universität München, Munich, Germany.
authors.forename: Erika
authors.initials: E
authors.lastname: Vojnic
authors.forename: André
authors.initials: A
authors.lastname: Mourão
authors.forename: Martin
authors.initials: M
authors.lastname: Seizl
authors.forename: Bernd
authors.initials: B
authors.lastname: Simon
authors.forename: Larissa
authors.initials: L
authors.lastname: Wenzeck
authors.forename: Laurent
authors.initials: L
authors.lastname: Larivière
authors.forename: Sonja
authors.initials: S
authors.lastname: Baumli
authors.forename: Karen
authors.initials: K
authors.lastname: Baumgart
authors.forename: Michael
authors.initials: M
authors.lastname: Meisterernst
authors.forename: Michael
authors.initials: M
authors.lastname: Sattler
authors.forename: Patrick
authors.initials: P
authors.lastname: Cramer
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D017405:Herpes Simplex Virus Protein Vmw65 / Q000378:metabolism*; D056892:Mediator Complex / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D017510:Protein Folding; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D015533:Transcriptional Activation
chemical_list: D017405:Herpes Simplex Virus Protein Vmw65; C483045:MED25 protein, human; D056892:Mediator Complex; D011994:Recombinant Proteins